This post is older than a year. Consider some information might not be accurate anymore.
To perform a release of your Maven Artifact, the pom.xml needs a SCM section. To validate or check if the SCM settings are correct, you can use the Maven goal:
Maven supports various SCM systems like Subversion (SVN), git or Mercurial (hg). See a current matrix which SCM systems and features are supported by the Maven release plugin.